This application is related to Japanese Patent Application No. 2000-191728 filed on Jun. 26, 2000, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an attachment structure of a gasket used as a seal member of a refrigerant pipe having therein a refrigerant such as carbon dioxide (CO2), that is used at a high-pressure.
2. Description of Related Art
When carbon dioxide or the like is used as refrigerant of a refrigerant cycle so that a high-pressure side refrigerant pressure becomes equal to or larger than the critical pressure, the refrigerant pressure becomes higher by 10 times or more, as compared with a general refrigerant cycle using flon as refrigerant. With the increase of the refrigerant pressure in the high-pressure side pipe, a seal member attached to a connection part of pipe members is need to be constructed by a compressive structure. For example, when an O-ring made of a porous material is used as a seal member for connecting pipe members, refrigerant readily penetrates the porous material, and sealing performance may be decreased. On the other hand, when a connection structure of the pipe members is sealed using a metal plate, because the metal plate cannot completely contact a seal surface, a gas leakage may be readily caused.
In view of the foregoing problems, it is an object of the present invention to provide an attachment structure of a semi-metal gasket for a refrigerant-seal, which improves a sealing performance of high-pressure refrigerant.
It is an another object of the present invention to provide an attachment structure of a semi-metal gasket having a deformation portion deformable in a thickness direction of the semi-metal gasket so that a leakage of high-pressure refrigerant is made in minimum.
According to the present invention, an attachment structure of a gasket for a refrigerant-seal includes a first connection member and a second connection member. The first connection member has a first opposite surface opposite to one side surface of the gasket, and a first wall surface opposite to one end surface of the gasket. Further, a second connection member has a second opposite surface opposite to the other side surface of the gasket and a second wall surface opposite to the other end surface of the gasket. The first and second connection members are disposed to define a seal space by the first and second opposite surfaces and the first and second wall surfaces, the gasket is constructed by a metal portion and both film coating layers provided on both side surfaces of the metal portion in a thickness direction to have a deformation portion deformable in the thickness direction. In the attachment structure, the gasket is disposed in the seal space in such a manner that the one end surface of the gasket is held on the first wall surface and the other end surface of the gasket is separated from the second wall surface by a predetermined clearance, before both the first and second connection members are fastened. Further, the gasket extends in an extension direction approximately perpendicular to the thickness direction, and the other end surface of the gasket press-contacts the second wall surface, after both the first and second connection members are fastened. When both the first and second connection members are fastened, the first end surface of the gasket presses against the first wall surface of the first connection member, and the second end surface of the gasket presses against the second wall surface of the second connection member to generate a reaction force. Due to the reaction force, the gasket presses both the first and second opposite surfaces of the first and second connection members, so that sealing pressure of the gasket is improved. As a result, even when the attachment structure is used for a refrigerant connection pipe through which high-pressure refrigerant flows, a sealing performance of high-pressure refrigerant in the refrigerant connection pipe is improved. Thereby, a leakage of high-pressure refrigerant can be made minimum.
Further, because the gasket is disposed in the seal space partially, the gasket can be manufactured in low cost, and the attachment structure of the gasket can be made smaller. Accordingly, fastening force for fastening both the first and second connection members can be made smaller.
Preferably, when a radial dimension of the gasket before fastening is as Lg, a radial dimension of the seal space is as Lb, and a radial dimension of the gasket after fastening is as Lgxe2x80x2, a ratio of Lg/Lb is equal to or larger than 0.85, and a ratio of Lgxe2x80x2/Lb is equal to or larger than 1. In this case, the seal pressure of the gasket can be further increased, and the leakage of the refrigerant can be further prevented.
More preferably, the ratio of Lg/Lb is in a range of 0.90-0.97. In this case, the effect of the present invention can be further improved.
Preferably, a thickness of each coating layer is in a range of 1-100 xcexcm. Accordingly, even when a material for forming the coating layer is changed, the leakage of the refrigerant can be prevented.